Ash, health and uncertainty

As ash from the Eyjafjallajöekull eruption in Iceland drifted across Europe earlier this month, the World Health Organisation (WHO) admitted that the health risks were uncertain. Contrasting news stories emerged. On 15th April, the BBC News Website published the reassuring headline, “Iceland volcano ash is ‘no threat to human health’.” The next day, The Daily Telegraph opened an article with a slightly more alarming title: “Volcanic ash can kill thousands but unlikely to drop on Britain.”

In a recent paper in Geography Compass, Gail Millar and others review methods for measuring the risk to human health from particulate matter – small particles of ash, dust or pollution suspended in the atmosphere. The difficulties of collecting information about volcanic ash rapidly become apparent. Flights were banned over the UK, so scientists were limited in their ability to collect data about the concentration of ash. The consequences of falling ash for people are also complicated by differences in the vulnerability of different individuals (e.g. children, the elderly) and their exposure (requiring knowledge about individuals’ activity).

Because extreme events are rare, there is clearly a need for more research into their outcomes. Geographers are well placed to understand the combination of physical and human processes that control the impact of extreme events.